A brushcutter, an engine blower, and a chain saw have been conventionally known as a portable work machine driven by an engine. The engine of such a work machine is driven at a position relatively close to an operator, and may be subjected to environmental regulations on a temperature of exhaust gas from a muffler. Therefore, it has been requested to exhaust the exhaust gas at a low temperature. Specifically, the temperature of the exhaust gas from an engine cover that covers the engine and the muffler is regulated.
As a method for lowering the temperature of the exhaust gas from an exhaust opening of the engine cover, for instance, it has been known that the exhaust gas is diffused and exhausted from an exhaust outlet of the muffler itself and a distance between the exhaust outlet of the muffler and the exhaust opening of the engine cover is lengthened to lower the temperature until the exhaust gas is exhausted from the exhaust opening (for example, see Patent Document 1).
[Patent Document 1] JP-A-2001-50047